The present invention relates to a kit or device and a method for administering gangliosides or ganglioside derivatives by inhalation for therapeutic purposes and to pharmaceutical compositions suitable for such administration. The pharmaceutical preparations according to the present invention are used to treat disorders of the nervous system resulting from accidents or diseases which have in some way damaged the nervous tissue.
Gangliosides are a group of glycosphingolipids and have a structure containing a carbohydrate portion to which is linked a ceramide and a sialic acid moiety. The carbohydrate portion includes at least one galactose or glucose moiety and at least one N-acetylglucosamine or N-acetylgalactosamine moiety. The general structure of a ganglioside can thus be represented by the following formula: ##STR1## where all of the moieties are linked by a glucosidic bond.
Numerous gangliosides have been identified and have been found to be particularly abundant in nerve tissue, especially in brain tissue. Various studies have shown that the most important of the sialic acids found in gangliosides are N-acetyl-neuraminic acid (NANA) and, to a lesser degree, N-glycolyneuraminic acid. Of the numerous gangliosides which have been identified, the following gangliosides, labeled by their international symbols, have been found to exist in significant amounts in ganglioside mixtures extracted from bovine brain tissue. ##STR2## where Glc represents glucose, GalNAC represents N-acetylgalactosamine, Gal represents galactose, NANA represents N-acetyl-neuraminic acid and the percentages in parenthesis indicate the amount of each ganglioside found in the ganglioside mixture extracted from bovine brain tissue.
It is known that gangliosides play an important role in the nervous system and it has recently been demonstrated that gangliosides are useful in the treatment of disorders of the peripheral nervous system and pathologies of the central nervous system (Adv. Exp. Biol. 71, 275, (1976)); Brain Res. 197, 236, (1980)); Acta Otoryngol. 92, 433-437 (1981); Muscle and Nerve 2, 382-389 (1979); Neuroscience 8, (3) 417-429 (1983); Neuroscience Letters, 34, 1-5 (1982); Eur. J. Pharmacol. 80, 243-245 (1982); Experientia 37, 301-302 (1981); Muscle and Nerve 5, 107-110 (1982); Neurochem. Int. 4, (2-3) 167-174 (1982); Neuroscience 7, 495-499 (1982); Muscle and Nerve 5, 351-356 (1982); Acta Diabetol. Lat. 20, (3) 265-276 (1983); Rev. Clin. Esp. 168 (3) 193- 198 (1983); Brain Res. 261, 163-166 (1983).
The therapeutic action of the gangliosides appears to consist mainly of stimulating sprouting phenomena in the nerve tissue and in activating the membrane enzymes involved in the conduction of nervous stimuli, such as the enzyme (Na.sup.+, K.sup.+) ATPase (Brain Res., 197, 236 (1980); J. of Neurochem., 37, 350 (1981)).
Nerve sprouting stimulated by the gangliosides will encourage restoration of the functioning of damaged nerve tissue.
Furthermore, it has been recently established that some ganglioside derivatives are more active than the gangliosides themselves in enhancing neuronal sprouting and in activating membrane enzymes implicated in the conduction of nervous stimuli, such as (Na.sup.+, K.sup.+) ATPase. These findings are the subject of applicant's co-pending applications Ser. No. 290,106, filed on Aug. 4, 1981, and Ser. No. 425,462, filed on Sept. 28, 1982, which are hereby expressly incorporated by reference. In particular, it has been established that inner ester derivatives of gangliosides are especially active in the treatment of nervous system disorders and are more active than the starting parent gangliosides. The inner ester derivatives of gangliosides are formed by the reaction between the carboxyl group of a sialic acid moiety with a hydroxyl group of one of the carbohydrate moieties or another adjoining sialic acid within the same ganglioside molecule (J. of Neurochemistry, 34, 1351 (1980); Bull. Mol. Biol. Med. 3, 170 (1978)).
For exemplary purposes, one possible inner ester derivative of a ganglioside could be represented by the following structure: ##STR3## wherein R in the sialic acid moiety is H or OH and R.sub.1 in the ceramide group is a fatty acid such as oleic, stearic or linoleic acid.
The inner ester ganglioside derivative (I) is an example of a derivative in which the carboxyl group of the sialic acid is ester bonded to a hydroxyl group of one of the carbohydrate moieties, specifically galactose. The formation of the inner ester bond, together with the normal glucosidic bond between the sialic acid and carbohydrate moiety, creates a lactonic ring, typically five or six-membered, characteristic of the structure of the inner ester ganglioside derivatives. While Formula I has been shown for exemplary purposes, it is to be noted that other lactonic rings having 5 or more membered ring structures could be formed as the sialic acid carboxyl group ester bonds with the hydroxyl group of a carbohydrate moiety.
As noted above, the inner ester ganglioside derivatives can also be formed when the carboxyl group of a sialic acid ester bonds to an adjoining sialic acid to which it is glucosidically bonded in the starting parent ganglioside. Such a structure could be represented by the following formula: ##STR4## wherein R.sub.2 represents the carbohydrate moiety which is glucosidically linked to the sialic acid moiety.
Another possible inner ester ganglioside derivative could be represented by the following formula: ##STR5## wherein R.sub.3 represents the carbohydrate moiety to which the adjoining sialic acid is ester bonded. Formula III then represents an inner ester ganglioside derivative in which a sialic acid is ester bonded to an adjoining sialic acid which is itself ester bonded to a carbohydrate moiety. It is therefore evident that many variations of the above described derivatives could be formed, so that the inner ester derivatives of gangliosides are generally formed of a carbohydrate portion, at least one ceramide and at least one sialic acid moiety wherein one or more of the sialic acids are ester bonded to a carbohydrate moiety and/or one or more of the sialic acids are ester bonded to an adjoining sialic acid. Numerous inner ester derivatives of gangliosides are thus possible, of which the above described are shown for exemplary purposes only.
Some prior methods for the preparation of inner ester ganglioside derivatives include the following:
1. The formation of internal esters by simply allowing the gangliosides to stand in an acetic or trichloroacetic acid solution (Sphingolipids, Sphingolipidoses and Allied Disorders, Adv. Exp. Med. Biol. 19, 95, (1972); J. Neurochem. 28, 1133, (1977)). PA1 2. The reaction of a water soluble carbodiimide with gangliosides in an aqueous medium (Carbohydr. Res. 41, 344, (1975)). PA1 3. According to the process disclosed in applicant's above-noted co-pending applications inner ester ganglioside derivatives are prepared by reacting gangliosides with a lactonization reagent in a non-aqueous organic solvent under anhydrous conditions. Suitable organic solvents to be used in the reaction include dimethylsulfoxide (DMSO), dimethylformamide (DMF), sulfolane, tetrahydrofuran, dimethoxyethane and pyridine or mixtures thereof. Suitable lactonization reagents include carbodiimides soluble in organic solvents such as dicyclohexylcarbodiimide, benzylisopropylcarbodiimide and benzylethylcarbodiimide, 2-chloro-1-methyl-pyridinium salts, ethoxyacetylene and Woodward reagent (N-ethyl-5-phenyllisoxazolium-3'-sulfonate).
The inner ester ganglioside derivatives can be used as drugs for the therapy of different pathologies of the nervous system, particularly peripheral nerve and central nervous system disorders. More particularly, the inner ester ganglioside derivatives can be used in the treatment of peripheral nervous system disorders due to traumatic, compressive, degenerative or toxic-infectious causes where the stimulation of nerve regeneration and recovery of neuromuscular function is necessary, and in central nervous system disorders due to traumatic, anoxic, degenerative or toxic-infectious causes where the stimulation of neuronal sprouting is necessary for functional recovery. These disorders have previously been treated by the use of gangliosides; however, the inner ester derivatives of gangliosides have much greater activity than that of the gangliosides themselves.
It has been determined that gangliosides and derivatives thereof act systemically. Accordingly, the compounds discussed above either as a single ganglioside compound, or as a single ganglioside inner ester derivative as such or in the form of pharmaceutically acceptable salts, or as a mixture of gangliosides or derivatives thereof, may be administered systemically in order to obtain a therapeutic effect. This administration may be in the form of a pharmaceutical preparation intended for administration and can be administered in man or in animals by intramuscular, subcutaneous or intradermal routes, by means of injections, or by means of intravenous infusions. However, it has not previously been known that these compounds are able to reach the blood stream by penetrating the biological membranes of the respiratory system.
The object of the present invention is the discovery that the gangliosides, as such, or in the form of pharmaceutically acceptable salts, as well as ganglioside derivatives, either singly or in mixture, may be administered by inhalation and that these compounds are readily absorbed by this route to reach the blood stream.